The invention primarily concerns a method for backfilling roadway supports in mine and tunnel constructions. The method utilizes the aid of support hoses filled with a hardening filling. The support hoses, in their empty state, are laid on the roadway support and subsequently filled with the hardener whereby they are inflated to a form locking profile with the roadway support.
The invention also relates to devices for carrying out this process with the use of a support hose made of water-permeable material, in particular textiles, which retain fine-grained components of the filler.
Generally, backfilling of roadway supports serves to avoid concentrated stress point loads by the rock on the roadway supports. This presumes that each roadway support on its periphery is abutted as far as possible directly against the rock surface through the backfilling; the rock surface is usually not excavated in exactly the same profile as the roadway, therefore the above presumption is highly unlikely to exist. The invention concerns the use of a hardening compound, preferably hydraulic filling compounds, which are pumped under considerable pressure, e.g. of 15 bar, as fluids into support hoses placed between the support sections and the rock formation in the area to be backfilled. The support hose, as it is filled with the hardening compound insures that the various gaps to the respective road supports are bridged, and at the same time connects the support section in a form locking relationship with the inflated profile of the support hose. In turn, the inflated profile of the support hose presses against the excavated rock surface or against a roadway lagging, which may be installed between the support hose and the rock formation and which is pressed against the rock as the support hose is pressurized with the filling.
Previously, this kind of backfilling technique could only be executed with U-channel iron sections. In that type of construction, the support hose is laid empty into the channel iron and is expanded into an inflated profile which rests on the bottom of the channel and in cross-section forms a lock between the bottom of the channel and both webs of the section. However, channel iron sections of this type are suitable only for yieldable roadway supports, as these consist of several sections therefore the channel iron sections must be joined together by placing one into the other and they must be braced yieldably to pressure in order to maintain the proper relationship. This does require special measures in order to form breaking points in the hardened filler in the area of the joints to allow the backfilling to yield sufficiently for the insertion of the sections.
This type of roadway support is part of the previously disclosed state of the art, German Pat. No. 26 27 256. The empty hose is inserted passing under the pressure yielding tension joints and into the bottom of the channel section. When the support hose is inflated, it will unfold completely to its desired inflated profile, producing the connection to the rock formation whereas between the overlapping zones of the sections, the hose is constricted to form the rated breaking points which make the insertion possible. It is a disadvantage that the overlapping zones cannot contact the rock. This portion can therefore give way when the roadway support is placed under excessive pressure, and it could distort the support to the extent that it can no longer provide the intended support. Further, channel sections are relatively expensive and can only be used where their great flexibility can be used to good advantage. These fields of use do not coincide with the much broader application of backfilling with the use of support hoses and hardening filler materials.
It has been known to use roadway supports which utilize yieldable supports as preliminary supports, such that when the yieldable supports are removed, contact is made with the rock by pillow-shaped hoses, which may also be inflated with a hardening filler as shown in Swiss Pat. No. 462 871. This type of support is recovered by dropping the pressure-yielding supports, thereby leaving a peripheral space with the support hoses or pillows and, accordingly, is limited in its recovery capabilities. For this kind of construction the support hoses must be common to two adjacent supports if they are merely laid onto the supports prior to being filled. Therefore only large volume hoses can be used in conjunction with small roadway support spacings, as occurs locally in crumbling rock.
The invention, however, has for its objective the task of applying the previously known back filling technique, which is not limited to specific support spacings, to generally I-beam shaped support sections used in multi-section roadway supports in conjunction with support hoses of known construction able to bridge spaces of approximately 25 cm. and are therefore relatively small in volume, and further to protect the joints between the sections against overload even if they are of limited yieldability.
According to the invention, this objective is attained by the identifying characteristics of the patent claims.
By directly placing and supporting the support hose onto the outer surface of a support flange which faces the rocks, the generally I-beam shaped roadway supports can be installed, in spite of the support hose, so that they are used in the principal load bearing plane or so-called y-axis of the support plane, their primary bending direction. The vertical support which was previously provided by the upright rocks of a U-shaped channel is now accomplished by allowing the support hose in its inflated form to extend over both sides of the top flange of the I-beam support thereby allowing the flange to indent the flexible support hose as it is filled and create a form locking indentation on each side of the flange of the I-beam support section upon which the support hose is laid. It is to be understood that this construction need only be used as desired in practical applications.
The invention therefore has the advantage of being able to place the support hoses also across the area of the support section joints and therefore also establishing a connection between these areas and the rock as well as joining the remainder of the periphery with the rocks. The joint sections are therefore not placed under excessive stress which avoids permanent deformation of the roadway support.
Usually the required lengths of hose are rolled off, e.g., a drum or a bobbin at the construction site, and the hose is then laid on the previously erected roadway support. Depending on the material, this kind of hose is resilient and, as the filler is introduced, it shapes itself not only from its original flat state into the cross-section of the inflated profile, but also within itself. It is therefore recommended, according to a preferred embodiment of the invention, to proceed in a way as to restrict the support hose in a manner that allows the hose limited lateral movement on the support flange while it is being filled. Thereby the hose can, for instance, move freely in its axis as it inflates until it has bridged the space, i.e. the gap to the rock formation.
It has been found that, contrary to prior experience with the U-shaped channel sections, mounting of the hose allowing limited movement does not need to extend over the full length of the support hose when using the hose in conjunction with an I-beam section flange, even though the bearing surface there is comparatively limited. For this reason, according to a further feature of the invention, the limited mobility of the support hose movement may extend over only portions of the support hose. The remaining portions of the support hose may be arranged to be freely movable. This method is of considerable advantage as it facilitates hose placement and, in particular, as it reduces the number or lengths of the auxiliary devices which need be provided on the support section for holding of the support hose on the I-beam support sections.
A further embodiment of the invention may also be realized, according to which the hose is form locked to the flange of the I-beam section in the area where its movement is restricted. The required devices can be spaced appropriately. The results of selective placement of this type of form lock means that parts of the form-fitting connections need only be provided on the support section and on the hose itself, so that auxiliary holding devices may be dispensed with.
It will not always be possible to adequately bridge all gaps in such a way as to form a contact with the rock as well as a form lock between the support hose and the I-beam support.
In particular, this may occur where unintended additional excavation was done due to teary rock or inadequate excavation. The method, according to the invention which is then practiced, is to establish a connection to the rock or the lagging by placing one or several short hoses on the side of the support hose facing the rock.
Here, too, the deformation occurring when the short hoses are filled can, without any additional mounting, be prevented from causing the short hoses to slip off or to deviate from the intended position without the use of additional mounting devices. For this purpose the method according to the invention provides that the short hoses are inflated at least on a portion of their length into a double bead, with which it is centered on the supporting hose.
According to an additional embodiment of the invention, one can proceed by placing the short hoses onto the supporting hose with a transverse fold, which is utilized as spare material when the respective hose is inflated.